Whether you find a new or used one, most stud welders will be 115vac powered. This should make it fairly easy to plug in and test them out prior to purchase. I'd take some scrap sheet metal, even if to a HF store, and explain that with your previous experience with the HF product you'd like to test it before leaving the store. Don't forget CL or even local pawn shops, perhaps you can still find a good used price on a better tool that would about equal the new HF price....